title: The effect of dexmedetomidine continuous infusion as an adjuvant to general anesthesia on sevoflurane requirements: A study based on entropy analysis.
abstract: BACKGROUND
  Dexmedetomidine, a α2 agonist as an adjuvant in general anesthesia, has anesthetic and analgesic-sparing property.
  
  
  OBJECTIVE
  To evaluate the effect of continuous infusion of dexmedetomidine alone, without use of opioids, on requirement of sevoflurane during general anesthesia with continuous monitoring of depth of anesthesia by entropy analysis.
  
  
  METHODS
  Sixty patients were randomly divided into 2 groups of 30 each. In group A, fentanyl 2 mcg/kg was given while in group B, dexmedetomidine was given intravenously as loading dose of 1 mcg/kg over 10 min prior to induction. After induction with thiopentone in group B, dexmedetomidine was given as infusion at a dose of 0.2-0.8 mcg/kg. Sevoflurane was used as inhalation agent in both groups. Hemodynamic variables, sevoflurane inspired fraction (FIsevo), sevoflurane expired fraction (ETsevo), and entropy (Response entropy and state entropy) were continuously recorded. Statistical analysis was done by unpaired student's t-test and Chi-square test for continuous and categorical variables, respectively. A P-value < 0.05 was considered significant.
  
  
  RESULTS
  The use of dexmedetomidine with sevoflurane was associated with a statistical significant decrease in ETsevo at 5 minutes post-intubation (1.49 ± 0.11) and 60 minutes post-intubation (1.11 ±0.28) as compared to the group A [1.73 ±0.30 (5 minutes); 1.68 ±0.50 (60 minutes)]. There was an average 21.5% decrease in ETsevo in group B as compared to group A.
  
  
  CONCLUSIONS
  Dexmedetomidine, as an adjuvant in general anesthesia, decreases requirement of sevoflurane for maintaining adequate depth of anesthesia.
authors.affiliation: Department of Anesthesia, B. J. Medical College, Civil Hospital, Ahmedabad, India.
authors.forename: Chirag Ramanlal
authors.initials: CR
authors.lastname: Patel
authors.forename: Smita R
authors.initials: SR
authors.lastname: Engineer
authors.forename: Bharat J
authors.initials: BJ
authors.lastname: Shah
authors.forename: S
authors.initials: S
authors.lastname: Madhu
keywords: Depth of anesthesia; dexmedetomidine; entropy; fentanyl; sevoflurane